Heat reversible viscosity of polymers

Adhesives, coatings, moldings, and polymer matrices with the capability to change from solid to viscous and back again


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The ability to selectively reduce polymer viscosity through heat or mechanical input allows one to readily remove or reposition an adhesive, heal a scratched coating, and even improve propellant emission performance. These desirable attributes have been attained by Army researchers with further benefits of reversing the reaction while maintaining stability and processing conditions of a conventional polymer.

The technical process for forming this reversible viscosity reducing polymer consists of a diene or a dienophile coupled to a moiety capable of reacting with a hydroxyl or amine group of an aliphatic polymer subunit which is reacted to obtain a polymer subunit with the exposed diene or dienophile. Subsequent reaction with complementary dienes or dienophiles necessary to form a Diels-Alder linkage terminates in a moiety capable of conventional cross-linking incorporating reversible viscosity characteristics. The viscosity of the fully cross-linked composition is controlled by the quantity of Diels-Alder linkages relative to the total number of cross-linkages.

To form the propellant mentioned above, the composition is mixed with an oxidizer such as NH4NO3, NH4ClO3, NH4ClO4, NaNO3O, NaClO3, NaClO3, KNO3, KClO3, KClO4, or other perchlorates; a particulate fuel; and other optional additives such as a burn rate modifier.

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